Strap joint



D80 30, 1941- J. w. LESLIE 2,258,339

STRAP JOINT Filed Sept. 7, 1940 2. ax 20) a IH' .figg i i 44- Z5 mi 'S y 6 Z0/ 1i? Q0 Patented Dec. 30, 1941 STRAP JOINT John W. Leslie, Chicago, Ill., assignor to Signode Steel Strapping Company, Chicago, Ill., a corporation of Delaware Application September 7, 1940, Serial No. 355,728

13 Claims.

This invention relates to strap joints.

More particularly, the invention is concerned with a joint for interconnecting overlapped portions of binding straps, which joints are made without the use of an encircling sleeve.

It is an object of my invention to provide a novel sleeveless strap joint that has a high breaking strength and a minimum weakening eiect upon the strap body.

Another object of my invention is to provide such a joint that can be formed easily with portable tools of feasible size.

An additional object of the present invention is to provide a novel sleeveless strap joint that is comparatively at and smooth.

Still another object of my invention is to provide a sleeveless strap joint in which the uppermost free end of the strap is closely held in a novel manner against the lower strap to prevent the free end of the strap catching in adjacent packages or bales or otherwise forming a hazard.

Other objects and advantages will become apparent hereafter in the description of my invention.

In the drawing, in which similar characters of reference refer to similar elements throughout the several views:

Fig. 1 is a plan view of overlapped portions of a strap that have been joined together according to my invention;

Fig. 2 is a plan view of the joint shown in Fig. l at one stage in its formation;

Fig. 3 is an enlarged vertical longitudinal sectional view of a portion of the joint, taken in the direction of the arrows along the line 3-3 of Fig. 1;

Fig. 4 is an enlarged vertical longitudinal sectional view, taken in the direction of the arrows along the line 4-4 of Fig. 2; and

Fig. 5 is an enlarged perspective View of a portion of one of the straps in the joint area, showing the manner in which the metal is cut and deformed to form the interlocking elements.

Referring to the drawing, the strap is passed around the package, bale or load to be strapped, and tensioned to bind `it tightly therearound. The overlapped ends I2 and I4 of the strap are then cut and deformed to form mutually facing interlocking elements which are slid and forced into engagement with each other by the strap tension when the joint forming tool is removed, or by other means.

In Figs. 1 and 2 the strap is shown as having four Z-shaped cuts I6, I8, 20 and 22 substantially equally spaced along the strap axis with alterthe strap thickness.

nate cuts I8 and 22 being the reverse comple` ments of cuts I6 and 20.

Each of these Z-shaped cuts in the embodiment shown is formed of two staggered parallel straight cuts 24 and 26 'extending generally lengthwise of the strap and connected by a diagonal cut 28 extending between the adjacent ends of the parallel cuts at an angle of about 35 thereto. The ap'exes 30 and 32 of the angles formed by this Z-shaped cut are somewhat rounded and form a pair of fingers 34 and 36 lying one on each side of the center line of the strap and pointing in opposite directions. These fingers 34 and 36 are bent one upwardly and one downwardly out of the plane of the strap so that the ends of the lingers 34 and 36 are spaced apart a distance equal to approximately twice This separation of the 1ingers from each other is accompanied by a gentle transverse curvature of the strap inthe vicinity of the Z-shap'ed cut. 'Ihat is, the metal on one side of the Z-shaped cut is curved outwardly from the plane of the strap in an upward direction, While the metal on the other side of the cut is similarly curved in the opposite direction. By thus forming the ingers 34 and 36, these lingers are spaced from the normal plane of the strap and are curved throughout their length so that planes tangential to their outward faces at their free ends are substantially parallel and parallel to the normal plane of the strap. This is best seen in Figs. 3, 4 and 5. This curving of the strap transversely forms a series of waves having high points 38 and low points 4U throughout the length of the joint.

Referring to Figs. 1 and 2, the joint shown is composed of four of the above described Z-shaped cuts arranged in spaced tandem alignment along the strap with alternate cuts being reverse complements of the other cuts.

As shown in Fig. 2 and in greater detail in Fig. 4, the overlapped ends of the strap are cui; and deformed together so that the overlying strap end I4 has its cuts and deformations in register with the similar cuts and deformations in the lower strap end I2. When the joint-forming tool is removed, the tension in the strap causes the strap ends to move slightly in the direction indicated by the arrows and forces the fingers to interlock. This is because `each Z-shaped cut provides a finger 36 on the upper strap which is jammed downwardly through a bight 44 in the lower strap and is wedged against the inner face of the linger 38 on the lower strap while a similar finger 36' on the lower strap is similarly jammed upwardly underlying strap immediately therebeneath are slightly kinked downwardly at 48 as shown in Figs. 2 and 4. This providesa hump at 48 in the lower strap portion over which the free end 46 lies with its end thus protected against becoming caught in adjacent bales or packages or otherwise forming a hazard. f I

It will be seen that a joint according to this invention is thin and smooth and has excellent holding power, while retaining maximum strength in the strap material. The arrangement of alternate cuts as reverse complements of each other neutralizes in one of these joint elements any tendency of the adjacent joint element to cause the strap ends to move laterally slightly with respect to each other as tension is applied; it also p-roduces a tendency toward creation of lateral or sidewise pressure or jamming with the result that the joint, when once drawn into tight interlocking relationship by tension, tends to retain that relationship in the event the tension on the strap is removed, thus preventing the strap ends from becoming separated; while the compound action of two or more tandem related joint elements gives the jointv exceptionally strong resistance to lateral attack.

Having thus described the nature and a preferred embodiment of my invention, what I claim and desire to secure by United States Letters Patent is as follows:

l. A strap joint comprising overlapped portions of metal strap cut and deformed to provide a pair of side by side fingers in each strap portion, one of said fingers extending obliquely upwardly from .the plane of its strap portionand the other said finger extending obliquely downwardly, each of said fingers being superposed upon substantially identical fingers in the second strapportion, said cuts and deformations being so arranged that slight longitudinal relative movement between the strap portions will force one of the fingers on the first strap portion through an opening in the, second strap portion and against one of the fingers on the second strap portion and simultaneously a finger on the second strap portion will be forced through an opening in the first strap portior.` and against a fingeron the first strap portion so that the strap 'portions are wedged together at or near the bases of the fingers.

2. A strap joint comprising overlapped portions of metal strap out and deformed to provide a pair of side by side fingers in each strap portion, one of said fingers curvingrobliquely upwardly from the p-lane of its strap portion and the other said finger curving obliquely downwardly, each of said fingers being superposed upon substantially identical fingers in a second strap portion and having the end portions of their outward faces tangential to planes substantially parallel to the undeforrned body of the strap, said cuts and deformations being so arranged that slight longitudinal relative movement between the strap portions will force one of the fingers on the first strap portion through an opening in the second strap portion and against one of the fingers on the second strap portion and simultaneously a finger on the second strap portion will be forced through an opening in the first strap portion and against a finger on the first strap portion, so that the strap portions are wedged together at or near the bases of the fingers.

3. A strap joint comprising overlapped portions of metal strap cut and deformed to provide a pair of vside by side fingers in each strap portion, one of said fingers extending obliquely upwardly from the planeof its strap portion and the other said finger'extending obliquely downwardly, each of said fingers being superposed upon substantially identical fingers in the second strap portion, said cuts and deformations being so arranged that slight longitudinal relative movement between the strap portions will force one of the fingers on the first strap portion through an opening inthe second strap portion and against one of the fingers on the second strap portion and simultaneously a finger on the second strap portion will be forced through an opening in the first strap `portion and against a finger on said first strap portion, and a second pair of side by side fingers in each strap portion, said second pair being arranged in tandem with the first pair and being formed as the reverse complements of the first pair.

4. A strap joint comprising overlapped portions of metal strap cut and deformed toV provide a pair of side by side fingers in each strap portion, one of said fingers curving obliquely upwardly from 'the plane of its strap portion and the other said finger curving obliquely downwardly, each of said fingers being superposed upon substantially identical fingers in the second strap portion and having the end portions of their outward faces tangential to planes sub-` stantially parallel to the undeformed body of the strap, said cuts vand deformations being so' arranged that slight longitudinal relative movement between the strap portions will force one of the fingers on the first strap portion through an opening in the second strap portion andagainst one of the fingers on the second strap portion and simultaneously a finger on the second strap portion will be forced through an opening in said first strap portion and against a finger on the first strap portion, and a second pair of side by side fingers inV each' strap portion, said second pair being arranged in tandem with the first pair and being formed as the reverse complements of the first pair.

5. A strap joint y comprising overlapped portions of metal strap cut and deformed to provide a pair of side by side'fingers in each strap por-` tion, one of said'fingers extending obliquely upwardly from the plane of its strap portion and the other said finger extending obliquely downwardly, each of said fingers being superposed upon substantially identical fingers in the second strap portion, said cuts anddeformations being so arranged that slight longitudinal relative movement between the strap portions will force one of the fingers on the first strap portion through an opening inv the second strapv portion and against one of the fingers on ythe second strap portion and simultaneously a finger Von said second strap portion will be forced through an opening in said first strapportion and against a nnger on the rst strap portion, and the free end of the overlying strap portion and the underlying strap portion therebeneath being deformed after the said longitudinal movement has occurred to provide a hump in one portion and a complementary deformation in the other portion.

6. A strap joint comprising overlapped portions of metal strap cut and deformed to provide registering interlocking elements adapted to be brought into interlocking relationship upon relative longitudinal movement between the strap portions, the free end or" the overlying strap portion and the underlying strap portion therebeneath being deformed to provide a hump in one portion and a complementary deformation in the other portion, said hump and complementary deformation being formed after the relative longitudinal movement has taken place between the strap portions.

7. A strap joint comprising overlapped portions of metal strap cut and deformed to provide a pair of side by side ngers in each strap portion with one of the iingers of each pair extending obliquely through an opening in the other strap portion, and the other of the fingers of each pair overlying the said first mentioned iingers.

8. A strap joint comprising overlapped portions of metal strap cut and deformed to provide a pair of side by side lingers in each strap portion with one finger of each pair extending obliquely through an opening in the other strap portion, the other fingers of each pair overlying the first mentioned ngers, and a second pair of side by side fingers in each strap portion in tandem with the first pair and formed as the reverse complements of the rst pair.

9. A strap joint comprising overlapped portions of metal strap having registering Z-shaped cuts along the center lines thereof, the metal contiguous to said Z-cuts being deformed to provide substantially longitudinally pointing side by side ngers, some of said ngers of one strap portion being deformed to extend through openings in the other strap portion and adapted to interlock with the metal contiguous to said openings upon relative longitudinal movement between said strap portions.

10. A strap joint comprising overlapped portions of metal strap having a plurality of registering Z-shaped cuts in tandem along the center line of the strap, the metal contiguous to said Z-cuts being deformed to provide substantially longitudinally pointing side by side ngers, some of said ingers of one strap portion being deformed to extend through openings in the other strap portion and adapted to interlock with the metal contiguous to said openings upon relative longitudinal movement between said strap portions and alternate Z-shaped cuts being the reverse complements of the other cuts.

l1. A strap joint comprising overlapped portions of metal strap having a plurality of registering Z-shaped cuts in tandem extending along the center line of the strap, the metal contiguous to said Z-cuts being deformed to provide substantially longitudinally pointing side by side fingers, some of said ngers of one strap portion being deformed to extend through openings in the other strap portion and adapted to interlock with the metal contiguous to said openings upon relative longitudinal movement between said strap portions, alternate ones of said Z-shaped cuts being the reverse complements of the other cuts and the overlapped strap portions being waved along each side in the region of said cuts with the waves along one side being substantially out of phase with the waves along the opposite side.

12. A strap joint comprising overlapped portions of metal strap joined together by two or more tandem related joints formed by cutting and deforming the strap material to form interengaging joint elements, said joints being inclined to the center line of the strap and the angle of inclination of one of said joints being diierent than the angle of inclination of another of `said joints, so that the tendency of one of the joints to cause relative lateral movement between the strap portions upon relative longitudinal movement thereof will differ from the similar tendency of another of the joints, thus producing lateral jamming of the joints upon relative longitudinal movement of the strap portions.

13. A strap joint comprising overlapped portions of metal strap joined together by two or more tandem related joints formed by cutting and deforming the strap material to form interengaging joint elements, said joints being inclined to the center line of the strap and the angles of inclination of alternate joints being reverse complements of each other so that the tendency of one group of said joints to cause relative lateral movement between the strap portions upon relative longitudinal movement therebetween will be counteracted by another group of said joints having a tendency to cause relative lateral movement in the opposite direction, thus producing lateral jamming of the joints upon relative longitudinal movement of the strap portions.

JOI-1N W. LESLIE. 

